In card counting, what exactly do index numbers mean?

Question

I have read about the Illustrious 18, and understand that if the true count is at or above the index number, that you should deviate from basic strategy. This is what I am confused about: What about the indexes that are negative? Example: 13 vs. 3 has an index of -2. Does that mean that if the running count is higher (more positive) that I should still hit on that? Or only if it is lower (more negative)?

Answer 1

The index number is the "true count" In order to get a true count, you must adjust the running count by the number of decks still un-played. If the running count is +3 and there are still 4 decks remaining in the shoe the true count is less than +1. If you have the same situation with 1 deck still to play, the count is a +3. In you example you would hit the 13 against the dealer's 2 if the "true count" was -2 or higher (-1, 0, or +) A "-2" count means that there are fewer ten cards in the remaining cards to play.The dealer is more likely to make a hand than break. You would hit in order to try and make a hand also and your chances of breaking are less.

I abandoned this count strategy several years ago as not being as profitable as a more instinctive approach. Sometimes you know the play and it is definitely not what the strategy shows. Profitability is affected more by the distractions of the table than missing the count. Heat, bad players, lucky dealers are huge factors.

Good luck

Answer 2

The indexs are numbers assigned to a play the marks the point where a play different from basic strategy becomes the more valuable option of all the plays you can make.

If the number asigned to it is positive, you will deviate when the TC is at or above the number.

If it is negetive you will deviate when the TC is at or BELOW the number,  

Negetive deviations are not that important since it is in your best interest not to be playing at all at negetive counts, however slightly negetive counts such as -1 may be frequent and those deviations should be learned.

There is an index play for every single hand, howveer some of the values are so extreme that a count of that value will never happen or is so unlikely to happen that it is not worth even memorising the play to begin with.

The i18 is comprised of the most important deviations based on how oftan they occur and how much EV they give you when they are used, all together the I18 represent ~90% of the ev that you would gain from using all 150 deviations.

Insurance is the most important deviation representing about 25% of all the ev you gain from deviations.

It is important to note that index numbers vary based on the card counting system that they are for, make sure that they are labeled of they come from the same book that outlines the system they are for.

in adition to the i 18 i recomend any index play that has a value of -1 though +8 as they are not that hard to memorise.

If you ever forget a index number always revert to basic strategy.